The present invention is a process for the production of silanes from the reaction of hydrogen chloride with silicon. The silicon may be in the form of silicon metal or a silicon containing material. The process employs a catalyst, selected from a group of metal and metal compounds, which increases production of tetrachlorosilane.
Much of the prior art is concerned with optimizing the reaction of hydrogen chloride with elemental silicon to form trichlorosilane and minimize production of other silanes, such as tetrachlorosilane. However, tetrachlorosilane is finding increasing industrial uses and, therefore, it is desirable to develop economical means for increasing tetrachlorosilane production from the reaction of hydrogen chloride and silicon metal or a silicon containing material.
British Patent No. 945,618, Published Jan. 2, 1964, describes a process for reacting metallic silicon with gaseous hydrogen chloride in the presence of a copper or copper-containing catalyst. The process is run at a temperature of 170.degree. C. to 350.degree. C. The process is reported to yield about 90% trichlorosilane with less than about 5% tetrachlorosilane being formed.
British Patent No. 1,530,986, Published Nov. 1, 1978,describes a method for the preparation of trichlorosilane and tetrachlorosilane by reaction of silicon or silicon-containing materials with hydrogen chloride in a fluidized bed at temperatures of from 250.degree. C to 500.degree. C. The reaction is carried out in the presence of from 0.2 to 10 parts by volume of gaseous silicon tetrachloride per part by volume of hydrogen chloride. Gaseous silicon tetrachloride is fed to the reactor both as a diluent for the gaseous hydrogen chloride and to maintain the homogeneity of the fluid bed.
None of the cited art teaches a process for the production of silanes which employs a catalyst effective in increasing the production of tetrachlorosilane from the reaction of hydrogen chloride with silicon.